[
https://issues.apache.org/jira/browse/HBASE-22448?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16845901#comment-16845901
]
Zheng Hu commented on HBASE-22448:
----------------------------------
Thanks for your work [~ram_krish]. Yeah, I think its here:
{code}
private ReturnCode calculateReturnCodeByPrevCellAndRC(Filter subFilter, Cell
currentCell,
Cell prevCell, ReturnCode prevCode) throws IOException {
if (prevCell == null || prevCode == null) {
return null;
}
switch (prevCode) {
case INCLUDE:
case SKIP:
return null;
case SEEK_NEXT_USING_HINT:
Cell nextHintCell = subFilter.getNextCellHint(prevCell);
return nextHintCell != null && compareCell(currentCell, nextHintCell) <
0 // ---> the comparison cost most of the CPU
? ReturnCode.SEEK_NEXT_USING_HINT : null;
{code}
> Scan is slow for Multiple Column prefixes
> -----------------------------------------
>
> Key: HBASE-22448
> URL: https://issues.apache.org/jira/browse/HBASE-22448
> Project: HBase
> Issue Type: Bug
> Components: Scanners
> Affects Versions: 1.4.8, 1.4.9
> Reporter: Karthick
> Assignee: Zheng Hu
> Priority: Critical
> Labels: prefix, scan, scanner
> Fix For: 1.5.0, 1.4.10
>
> Attachments: 0001-benchmark-UT.patch, HBaseFileImport.java,
> org.apache.hadoop.hbase.filter.TestSlowColumnPrefix-output.zip,
> qualifiers.txt, scanquery.txt
>
>
> While scanning a row (around 10 lakhs columns) with 100 column prefixes, it
> takes around 4 seconds in hbase-1.2.5 and when the same query is executed in
> hbase-1.4.9 it takes around 50 seconds.
> Is there any way to optimise this?
>
> *P.S:*
> We have applied the patch provided in
> [-HBASE-21620-|https://jira.apache.org/jira/browse/HBASE-21620] and
> [-HBASE-21734-|https://jira.apache.org/jira/browse/HBASE-21734] . Attached
> *qualifiers*.*txt* file which contains the column keys. Use the
> *HBaseFileImport.java* file provided to populate in your table and use
> *scanquery.txt* to query.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
